GB2142569A

GB2142569A - Copy lathe

Info

Publication number: GB2142569A
Application number: GB08413046A
Authority: GB
Inventors: Robert Horn
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-05-24
Filing date: 1984-05-22
Publication date: 1985-01-23
Also published as: AU573220B2; NZ208257A; GB8413046D0; DE3419323C2; ZA843950B; CA1224350A; GB2142569B; US4628975A; DE3419323A1; AU2850484A

Description

1 GB 2 142 569 A 1

SPECIFICATION

Lathe This invention relates to a copy lathe which is 70 particularly suitable for wood turning although it can also be used for turning other materials, including certain soft free machining metals, fabricated bake lite and the like.

Background of the invention

Although highly skilled operators can frequently copy one turned workpiece with another, the copying has minor inaccuracies, and a less skilled operator often has difficulty in making two products look similar, yet it is quite important in many applications that they should have similar appear ance, for example the stanchions of a banister or staircase rail.

These problems have been recognised and the reader's attention is directed to the U.S. Patent No. 3,768,527 (Messick) and 4,256,155 (Hochstatter et al). The Messick disclosure shows a flat plate arranged to be secured to a flat lathe bed and to have on it a freely movable tool, the base plate having a first arm that supports a pattern follower and a second arm which supports a second cutting tool above and in vertical alignment therewith. Howeverthere is an inherent difficulty in the use of such a tool, in that it is limited to a "short toe", and should the tool "dig W' to the workpiece, it will tend to both tilt about the toe of the base plate and also bend the base plate and column, and a workpiece can be damaged by such an occurrence.

The main object of this invention is to overcome such problems and in this invention the pattern, or template, is supported on surfaces which place it above the bed of the lathe, and the base of the tool holder has its toe projecting forwardly beyond the follower guide and beneath the template.

Brief summary of the invention

Briefly in this invention a copy lathe is provided with template supports projecting from both head stock and tail stock which support a template above 110 the bed, and clamp means clamp the template to the support means, there being provided a tool holder having a follower guide thereon which extends vertically upwardly from a base, the toe of the base however extending forwardly beyond the follower guide and beneath the template, the tool holder having a tool locked thereinto with the cutting edge of the tool vertically above the follower.

More specifically, the invention consists of a copy lathe having a flat bed, a head stock on the bed, a tail 120 stock on the bed, a shaft rotatable in the head stock and a sleeve in the tail stock both having a common turning axis, template support means projecting from both said head stock and tail stock, having template support surfaces lying in a common plane above the bed, and clamp means co-operable with both said template support means operable to clamp a template thereto, a tool holder having a vertically extending follower guide thereon, and locking means for locking a tool therein, said tool holder having a flat base the toe of which extends forwardly beyond the follower guide, such that, when a cutting tool is locked in the tool holder and has its cutting point vertically above said follower, reaction of downward pressure applied to the cutting tool when cutting a workpiece is within the area of the base, and the toe lies wholly below said common plane so as to be positionable beneath said template when clamped to said support means.

With this invention the toe of the base of the tool holder is positioned so far forwardly of the tool that the downward reaction, for example due to the tool entering a workpiece by an excessive amount, is within the periphery of the base plate and tilting cannot occur. A surprising degree of rigidity and stability is achieved.

In an embodiment of the invention the flat bed has a tail stock guide slot extending along it, but the toe extends beyond the tool holder follower guide by a sufficient distance to bridge the slot before the follower guide can contact a template, this being the worst condition.

Sometimes it is required to machine a workpiece with a face cut, that is, by moving a cutting tool transversely, for example for producing a bowl or drinking vessel, and in an embodiment of the invention the template support means which projects from the head stock extends across the bed for most or all of the width of the head stock, the head stock is provided with a pair of transversely spaced clamping screws so that the template can be so clamped that its edge to be followed faces the tail stock. The tail stock clamping screw is longitudinally aligned with the rear of the head stock clamping screws.

Sometimes it is desired to avoid making a template and directly copy from a model which may have been itself produced by a turning operation, and to achieve this there can be provided a pair of co-axial pins extending from the head stock and tail stock, at least one of the pins having threaded adjustment means so that it can clamp a model against the other pin, the pins constituting "centres" for retaining the model.

Brief description of the drawings

An embodiment of the invention is described hereunder in some detail with reference to and is illustrated in the accompanying drawings, in which:

Figure 1 is a plan view of a copy lathe, Figure 2 is a fragmentary elevation of same but drawn to an enlarged scale, Figure 3 is a plan view of a tool holder and tool, Figure 4 is an elevation of Figure 3, Figure 5 is an end elevation of Figure 4, Figure 6 is a perspective view of an electric tool holder for holding a power tool, and Figure 7 is a plan view showing a tool sharpening abrasive wheel and follower location bar.

In this embodiment a copy lathe 10 is provided with a flat bed 11 and a head stock 12 on the bed 11.

A tail stock 13 also on the bed 11 is guided by the surfaces 14 of slot 15 for longitudinal movement, the head stock 12 having a rotatable shaft 17 journalled in bearings (not shown) in the head stock and the tail 2 GB 2 142 569 A 2 stock 13 having a sleeve 18 which is co-axial with the shaft 17 and defines therewith a common turning axis A1 which is parallel to the bed 11 but displaced upwardly therefrom.

Aflat plate 20 projects from the tail stocktowards the head stock and a second flat plate 21 projects from the head stock towards the tail stock, the plates and 21 having upper surfaces which are template support surfaces to support a template 22 above the bed 11, the template 22 being clamped to the plates and 21 by clamping screws 23 and 24 respectively which are longitudinally aligned with each other, the clamping screw 23 threadably engaging a bracket 25 which extends from the tail stock and the screw 24 threadably engaging a bracket 26 which extends from the head stock. A second bracket 27 also extends from the head stock and carries in it a third screw 24, and is usable for clamping the template 29 when such is used in lieu of template 22, for example for machining a bowl or drinking vessel wherein face cuts are required.

Figures 3,4 and 5 illustrate details of the tool holder 32 (not shown in Figure 1) the tool holder 32 having two flat guide surfaces 33 and 34 which converge forwardly to define a vertically extending follower guide edge 35, and the tool holder also has a tool 36 clamped in a forwardly extending tool retaining sleeve 37, the tool being locked into position by a pair of locking screws 38, with the cutting point 39 of the tool being vertically above the 95 follower guide edge 35. The tool holder comprises a base 41 having a post 42 extending upwardly from its heel 43, and joining the tool retaining sleeve 37 is the base 41, the base 41 also having a toe 44 extending forwardly. When downward foce "F" is applied to the cutting point 39 of the tool 36 it is resisted by upward reaction against the base 41, this upward reaction extending over the whole area of the base 41 between the toe R1 and the heel R2. The toe 44 extends forwardly sufficiently to bridge the slot 15 of the bed so that stability of the tool holder 32 exists under all conditions of use. The depth of toe 44 is less than the space between template 22 or 29 and the bed 11 so that the toe 44 can extend beneath the templates during turning. The peripher110 al shape of base 41 is best seen in Figure 3 and includes a pair of laterally projecting protuberances 47 and 48 on each side, between which is a respective recess 49, this shape being convenientfor grasping with either the left or right hand by an operator. The tool can be used at any angle and still faithfully follow its pattern or template. In some embodiments, a thin wall "glove" or cover extends over the nose of the follower guide, and, upon removal, enables the tool to make a finish cut the depth of which is only the metal thickness of the glove.

The shaft 17 projects rearwardly from the head stock 12 and has secured to it an abrasive wheel 51 contained under a guard 52 hinged to the head stock, there also being provided a follower location bar 53 having a flat location surface 54 which is parallel to the cutting face of the wheel 51 and is located beneath the cutting zone, the arrangement being such that when the flat guide surface 33 or 34 is located against the location surface 54, the cutting tool 36 can be sharpened along surfaces which converge forwardly corresponding to the convergence of the surfaces 33 and 34. The location bar 53 is clamped by a clamping bolt 56 in the sleeve 57 on a mounting bracket 58 secured to the lathe bed 11, such that the location bar 53 can be retracted as wear on the abrasive wheel 51 reduces its diameter.

Sometimes there is a requirement to cut grooves in a workpiece, or to draw holes inclined at an angle with respect to the longitudinal axis of the workpiece, and Figure 6 illustrates an electric tool holder 61 having a base 62, a guide plate 63 upstanding from the base and also having a pair of guide surfaces 33 and 34 which converge forwardly to the follower guide edge 35, as in Figure 4. A bifurcate tool clamp 65 comprises a pair of arms which are arranged to grip an electrictool (for example a drill or router) when drawn together by a clamping screw 66. As shown in Figure 1, there is provided a mounting block 68 secured to the front edge 69 of the bed 11 by bolts 70, but the bolts engage nuts which bear against a rear surface of a bar (not shown) such that the mounting block 68 can be clamped in any one of a plurality of positions along front edge 69. A guide bar 71 is carried by mounting bracket 68 and adjustable for angle, being locked at a selected angle by a locking screw 72, and this can guide the electric tool holder 61 to move towards or away from a workpiece at various angles.

Sometimes it is necessary to copy a model instead of copying the shape of a template, and in this embodiment there are provided a pair of co-axial pins 74 and 75 extending respectively from the head stock 12 and tail stock 13, each pin having a pointed end 76, at least the pin 75 threadably engaging its tail stock 13 to provide thread adjustment means for adjusting the distance between pins 74 and 75, the pins lying centrally in the same central vertical plane which contains the head stock shaft and tail stock sleeve, and defining a second axis A2 parallel to and vertically below axis A. A model positioned between the pins 74 and 75 and clamped in that position by actuation of the thread clamping means, is engaged by the follower guide edge 35 as in the case of a template shape being followed.

Claims

1. Acopy lathe having a flat bed, ahead stockon the bed, a tail stock on the bed, a shaft rotatable in the head stock and a sleeve in the tail stock both having a common turning axis, template support means projecting from both said head stock and tail stock, having template support surfaces lying in a common plane above the bed, and clamp means co-operable with both said template support means operable to clamp a template thereto, a tool holder having a vertically extending follower guide thereon, and locking means for locking a tool therein, said tool holder having a flat base the toe of which extends forwardly beyond the follower guide, such that, when a cutting tool is locked in the tool holder and has its cutting point vertically above said 3 GB 2 142 569 A 3 follower, reaction of downward pressure applied to the cutting tool when cutting a workpiece is within the area of the base, and the toe lies wholly below said common plane so as to be positionable beneath said template when clamped to said support means.

2. A copy lathe according to claim 1 wherein the surface of said bed is flat, and contains a tail stock slot defined by tail stock guide surfaces which guide the tail stock for movement along the bed, the space between the tail stock guide surfaces being less than the distance by which said tool holder toe extends forwardly beyond the follower guide.

3. A copy lathe according to claim 1 wherein said template support means projecting from said head stock extends across the bed for most of the width of the head stock, and said clamp means comprise a pair of transversely spaced clamping screws threadably engaging brackets projecting from the head stock.

4. A copy lathe according to claim 3 wherein said clamp means comprise a further clamping screw threadably engaging a bracket projecting from the tail stock, said further clamping screw being in longitudinal alignment with one of said head stock clamping screws.

5. A copy lathe according to claim 1 further comprising a pair of horizontal co-axial pins extending respectively from the head stock and the tail stock, each said pin having a central pointed end, at least one of said pins having threaded adjustment means thereon for adjusting the distance of its pointed end from the pointed end of the other pin, said pins lying centrally in the central vertical plane of the head stock shaft and tail stock sleeve.

6. A copy lathe according to claim 1 wherein said follower guide is a vertical edge between two flat guide surfaces of the tool holder which converge forwardly, said lathe shaft extending rearwardly of the head stock, a tool sharpening abrasive wheel on the lathe shaft rearward extension, and a follower location bar having a flat locating surface, and clamped to the lathe bed beneath the cutting zone of the abrasive wheel, such that when a flat guide surface is moved in contiguity with said flat locating surface, a side edge of a tool when locked in the tool holder is brought into contact with the abrasive wheel, and said contact sharpens the tool along surfaces which correspondingly converge forwardly.

7. A copy lathe according to claim 1 wherein said tool holder comprises a forwardly extending tool retaining sleeve, and a post extending upwardly from the heel of the base to the rear end of the sleeve, said locking means comprising a metalthread screw in the wall of the sleeve which bears against a surface of a tool when in the sleeve.

8. A copy lathe according to claim 1 or claim 6 wherein the peripheral shape of the base includes a pair of laterally projecting proturberances on each side of the base, and a recess between the protuber- ances, said peripheral shape being symmetrical about a central plane.

9. A copy lathe according to claim 1 further comprising an electric tool holder having a base, a guide plate on the base having two flat guide surfaces which converge forwardly and terminate in a vertical follower guide edge, a bifurcate tool clamp located above and rearwardly of the guide plate, and a clamping screw joining the limbs of the tool clamp.

10. A copy lathe according to claim 9 further comprising a mounting block, means securing the mounting block to the lathe bed near its front edge adjustably for position, a guide bar pivoted to the mounting block, and a locking screw releasably securing the guide barto the mounting block, the guide bar guiding the electric tool holderfor movementtowards or away from the turning axis.

11. A copy lathe substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Printed in the UK for HMSO, D8818935,11184,7102. Published by The Patent Office, 25Southampton Buildings, London, WC2A lAY, from which copies may be obtained.